The statement that Plato did not hear Socrates speak until he
was twenty is attributed by Diogenes himself (3.6) to mere
hearsay and introduced as part of the improbable drama of the
burning of the tragedy. It is most unlikely that the young
kinsman οf Critias and Charmides had to wait so long for the
privilege. Another early philosophical acquaintance is said to
have been Cratylus the Heraclitean. Aristotle(Metaphysics
987a32) says that Plato was acquainted with him ‘from his
youth’, Diogenes (without mention of source) that he ‘attached
himself’ to him after the death οf Socrates.[14]
There is probably some confusion here, especially as Diogenes
(3.5) says that before he heard Socrates, Plato was a
Heraclitean in philosophy. Aristotle is more likely to be right,
but the chronological sequence is unimportant for the point
which he is making, namely that Plato’s two-world metaphysics
was the product of an abiding faith, inherited from Socrates,
that permanent and stable realities exist combined with a
Heraclitean conviction that the whole sensible world was an
endless flux of change and instability. Even after Socrates’s
death, Plato was only twenty-eight, and had another fifty years
of life and philosophy ahead of him.[15]